1. Background Field
The subject matter disclosed herein relates to electronic devices, and more particularly to methods, apparatus and articles of manufacture for use in identifying and/or accessing one or more authorized location servers and/or one or more location services.
2. Information
Mobile devices, such as mobile phones, notebook, computers, etc., typically have the ability to estimate their location and/or position with a high degree of precision using any one of several technologies such as, for example, satellite positioning systems (e.g., GPS, Galileo, Glonass and the like), advanced forward link trilateration (AFLT), Cell ID or Enhanced Cell ID just to name a few examples. Location or position estimation techniques typically involve the processing of measurements which may be based on signals acquired at a mobile device receiver. For example, a mobile device may acquire satellite positioning system (SPS) signals or pilot signals transmitted from terrestrial base stations. Various measured characteristics of the acquired signals such as phase, signal strength, time of arrival, and/or round trip delay may be used in computing a position fix.
In a particular implementation, User Plane (UP) positioning such as SUPL (Secure User Plane Location) as set forth by the Open Mobile Alliance (OMA) in publicly available documents describe a framework within which location estimates obtained at a mobile device (e.g. a SUPL Enabled Terminal (SET)) or at a separate location server (e.g. SUPL Location Platform (SLP)) may be made available to other entities as part of a location service. Making these location estimates available to other entities may be useful in particular applications such as, for example, providing emergency services, locating a user on behalf of another client user, obtaining driving directions or finding a nearby gas station, hotel, airport or hospital. Additionally, in certain instances a mobile device may also communicate with an SLP to obtain positioning assistance data such as, for example, a rough location, accurate time reference, data to assist in acquisition of SPS or terrestrial radio signals, local indoor navigation assistance data, SPS ephemeris data to assist in computing a location from SPS measurements just to name a few examples of positioning assistance data.
A location estimate may be referred to as a location, estimated location, position or position estimate—these terms being used synonymously herein.
In certain instances, an external client may comprise a SUPL Agent. A SUPL Agent may indirectly acquire an estimated location of a SET from the mobile device. For example, to acquire an estimated location of a mobile device, a SUPL Agent may transmit a message to an SLP requesting the estimated location. After receiving the message from the SUPL Agent, the SLP may initiate a SUPL session with the mobile device to obtain an estimated location of the mobile device, which may subsequently be transmitted from the SLP to the SUPL Agent. The estimated location may typically be obtained in one of two ways—either (i) where the mobile device makes measurements (e.g. of SPS signals and/or terrestrial radio signals from nearby base stations and/or other wireless access points) and transfers the measurements to the SLP for the SLP to compute the estimated location or (ii) where the mobile device makes measurements as in (i) and in addition computes the estimated location itself, possibly making used of assistance data (e.g. SPS ephemeris data) provided by the SLP in order to do this.
In one particular example, a mobile device may be associated with a home location server such as a home SLP (H-SLP) having location assistance data that is generally applicable to regions where the user device may be located at any particular time. Here, regardless of a current location of the mobile device, the mobile device may communicate with its H-SLP to obtain various location services, positioning assistance data, location based service information, etc.
In certain situations, however, an H-SLP may not have a particular location service and/or certain desired positioning assistance data, etc., for a mobile device to use in obtaining navigation assistance. For example, if the mobile device is located inside a building structure such as a shopping mall, airport, civic center or hospital (to name just a few examples), the H-SLP may be able to provide assistance data related to nearby base stations external to the building structure and to certain SPSs, but may not have information on wireless access points inside the building structure such as Wireless LAN Access Points or Femtocells. In that case, it may not be possible to obtain an accurate location estimate for the mobile device—e.g. if the mobile device can measure signals from the wireless access points inside the building structure but due to signal attenuation and reflection caused by the building structure, is unable to measure or accurately measure signals from SPS satellites and external base stations. In certain other cases, the H-SLP may not know about base stations nearby to the mobile device (e.g. if the mobile device is in a country or region remote from the H-SLP) making location estimation difficult or impossible even when the mobile device is outdoors and not within a building structure. Thus, it may be beneficial for a mobile device to be able to obtain certain location service(s), positioning assistance data, location based service information, etc., in some other manner.
In still other situations, it may be that given a location of a mobile device and/or current operations of an H-SLP, that the H-SLP may be unable to assist in providing a particular location service, etc., in some adequate and/or timely manner. Thus it may be beneficial for a mobile device to be able to obtain certain location service(s), a positioning assistance data, location based service information, etc., in some other manner.